1. Field of the Invention
The present invention relates to a control device of a variable cylinder engine.
2. Description of the Related Art
Known in the art is a variable cylinder engine designed so that the cylinders are divided into a first cylinder group and a second cylinder group, a first intake manifold connected to the first cylinder group and a second intake manifold connected to the second cylinder group are connected to a common intake passage, a throttle valve is disposed in that common intake passage and an intake cutoff valve is disposed in the inlet portion of the second intake manifold, the intake cutoff valve is fully opened when all the cylinders are to be operated, and the intake cutoff valve is closed to cause the inflow of intake air to the second cylinder group to stop and the supply of fuel to the second cylinder group is made to stop when the second cylinder group is to be made idle and partial cylinder operation engaged in (see Japanese Unexamined Utility Model Publication (Kokai) No. 59-152155).
With this engine, however, sufficient consideration was not given to the rapid changes in the engine output torque caused by the switching operation of the intake cutoff valve when shifting from full cylinder operation to partial cylinder operation or when shifting from partial cylinder operation to full cylinder operation and therefore there was the problem that the engine suffered from rapid changes in the engine output torque when the number of operating cylinders was changed.